If a Stateful Session Bean is accessed and then goes into passivation and an exception occurs, the next call to get the SFSB gets stuck in an infinite loop looking for the SFSB key in this class:
ejb3/src/main/java/org/jboss/as/ejb3/cache/impl/backing/PassivatingBackingCacheImpl.java
It appears PassivateTask is scheduled with a thread pool, it attempts the passivation and logs the exception that occurs, but the SFSB key does not appear to be removed when passivation fails, this results in the infinite loop above.
./src/main/java/org/jboss/as/ejb3/cache/spi/impl/PassivateTask.java

If a SFSB fails to passivate it should not be destroyed. (Though this is allowed by spec.)
This might become a configuration option in the future.
Thus bug is purely about the infinite loop that occurs.